Apparatuses such as inkjet printers or the like have a liquid-drop ejection head for ejecting liquid drops and a tank for supplying a liquid to the liquid-drop ejection head. For example, JP-A-2004-9450 describes an inkjet printer including an inkjet recording head which is mounted on a carriage and a main tank. In addition, a sub-tank is further provided on the carriage. Ink from the main tank is supplied to the inkjet recording head via the sub-tank.
In addition, an air-permeable member (a gas-permeable membrane) is provided with the sub-tank in the printer of JP-A-2004-9450. The air-permeable member is configured to not allow the ink to permeate therethrough but to selectively allow air to permeate therethrough, whereby air within the sub-tank is removed through the air-permeable member, and air and liquid are thereby separated from each other within the sub-tank. Accordingly, a problem can be suppressed that air is caused to flow into the liquid-drop ejection head's side.
However, according to the knowledge of the inventors of the present application, it is found that if ink leak out from the air-permeable member and the ink that has so leaked remain on the air-permeable member, air is made difficult to permeate through the air-permeable membrane in the area where the ink remains. This may causes that air and liquid cannot easily be separated from each other.